Coronary heart disease (CHD) is the single leading cause of death in America. Many studies demonstrate the critical importance of shortening the time from acute myocardial infarction (AMI) symptom onset to treatment. Although differing opinions exist regarding time-to-treatment guidelines, many physicians suggest the time-to-treatment goal should be one hour. Meeting this goal is often not practical due to the fact much of this “golden hour” is commonly consumed by patients wondering if the symptoms they are experiencing are related to a heart attack or simply another non-life threatening physiological condition (e.g., heartburn, sore muscles, etc.). Patients usually rush to the hospital when they suffer extremely painful heart attacks, but many heart attacks are only accompanied by relatively minor discomfort that, while obviously present, can be easily confused with non-threatening conditions. By the time the patient decides to seek medical help, much or all of the “golden hour” has often passed.
Historically, acute myocardial infarction (AMI) has been diagnosed by a physician when the patient is experiencing ischemic chest pain typically associated with AMI and electrogram (EGM)/electrocardiogram (ECG) signals have characteristics typically associated with AMI (e.g., ST segment elevation and pathological Q-waves). It has been difficult for prior medical devices, either implantable or external, to detect AMI with satisfactory levels of sensitivity and specificity based on measured EGM/ECG signals. For example, ST segment deviations may not necessarily be due to AMI but could be due various other artifacts. This difficulty in detection has led to the late recognition of AMI and action by the patient in seeking assistance, thereby leading to long delays until therapies are delivered to the patient.